1. Field of the Invention
This invention relates to a device for transverse sizing of printed products such as in a rotary offset press, and for a corresponding process for sizing the printed products.
2. The Prior Art
In the prior art, there are roller transverse sizing units with a perforated plate, in which the holes are mechanically opened in a sizing position by a common seal. This system has the disadvantage that it can get dirty very easily and requires a great deal of servicing due to the common seal for all of the holes. Furthermore, this system is complex and expensive. In addition, the sizing is simply pressed out of the holes with this system, which also causes a great deal of soiling. Moreover, the sizing is always applied over the entire length of the set of holes.
Other prior art devices include electronically-controlled nozzle transverse sizing units with individual seals of a sizing application device. These nozzle transverse sizing units are static in relation to the moving printed product, so that a satisfactory pattern can be applied only up to certain speeds due to the mechanical and electrical tolerances of the application devices and the tear-off behavior of the sizing dots.
It is therefore an object of the present invention to provide a device and a process for transverse sizing of printed products that is easy to service and produces sizing of a high quality.
These and other objects of the invention are accomplished by a device for transversely sizing printed products that uses individual application devices that are provided on a roller. The method includes moving individual application devices in at least one sizing position where the relative speed between the application devices and printed product is held at essentially zero.
In the present context, xe2x80x9cindividual application devicesxe2x80x9d comprise each component of an application device that contacts the sizing and can be removed individually from a roller for servicing, and which can be attached to the roller independent of other application devices. In particular, these can be individual nozzles or nozzle heads or parts.
To make servicing easier, at least one exchangeable holder is provided on the roller for at least one applicator. There can also be several applicators in the holder. An exchangeable module can be provided in the roller that has at least two holders. With this arrangement, cleaning is made easier and one can adapt to changed conditions. The down time required for such jobs is reduced and the machine time is thus increased.
The flexibility of the arrangement according to the invention can be increased when the applicators are individually controllable or controlled. Without constructional measures, the manner in which the sizing is applied by the individual applicators and the length of the sizing path can be adapted. In particular, the individual control of the applicators allows the applicators to be supplied with sizing by a common feed without abandoning the advantages of the invention.
Depending on the requirements, the individual applicators can be controlled in groups or blocks to reduce the complexity of the controlling. Simple and flexible control is achieved by electrically controlling at least one of the applicators.
The risk of soiling can be further reduced if the applicators spray the sizing onto the printed product. This is best achieved by nozzles. If the nozzles are electrically controlled, the applied sizing can be easily and precisely dosed. The nozzles can also have a pump that transports the sizing in response to an electrical control. This can provide particularly fine and finely adjusted dosing.
To reduce impurities, the nozzles apply the sizing without contacting the printed product. Alternatively, application with contact is also possible.
To prevent the nozzles from drying out or to reduce drying when the device is not used, a gate is provided for covering the nozzles. A gate can be used for all or some of the nozzles and is actuated by a pneumatic actuator.
The sizing is applied evenly when the applicator is moved synchronous with the movement of the printed product. This can be guaranteed when the roller with the applicators is rotated at a corresponding speed.
The device and process are particularly simple when the roller is designed to retain the format of the printed product, i.e., when the perimeter of the roller is a non-fractional multiple of the length of the printed product, or the length of the printed product corresponds to a non-fractional multiple of the roller perimeter. Preferably, the perimeter of the roller identically corresponds to the format of the printed product.